Since they would be making the invitations themselves, [Bill] and [Mara] needed a simple circuit that could be easily mass produced. They turned to the classic microcontroller-powered blinking LED circuit powered by an ATtiny13.

The first order of business was producing 50 printed circuit boards for each of the invitations. For this, [Bill] picked up an Xerox Phaser laser printer off of ebay and a few sheets of copper-clad kapton film. The etch resist was printed directly onto the kapton film and etched in a bath of ferric chloride, effectively making a flexible PCB.

These circuit boards were soldered up and laminated between the printed invitation and the card stock cutter with the help of a Silhouette Cameo paper cutter. After the cards were assembled, the battery was wired up and the cards shipped out.

The microcontroller inside the card was programmed to be asleep most of the time, waking up only every few seconds to check a light sensor to determine if the card was opened or not. If the microcontroller sensed the card was open, the lights began blinking, making it one of the most memorable wedding invitations [Bill] and [Mara]’s guests will ever receive.

Oh this one’s good! This clock has a built-in WWVB receiver to make sure the time is always accurate. But with just one LED as the display we wish you good luck when reading it! A whole bunch of info (time, day, year, etc) is blinked out in binary encoded decimal. [Thanks Tymm]

Standard Time

Manual labor. This clock is an art installation in Rotterdam. In the video you can see that workers changed the segments of a four-digit display every minute over a twenty-four hour period. Since they filmed it we’d expect the ability to turn this into a video clock like the one we saw last week. [Thanks David]

International Clock

Low-tech but highly creative. The instructional video uses basic geometry and the workings from a cheap clock to craft an international clock. There are twelve labels corresponding to different time zones. Put the zone you want up and read the clock as normal. [via Red Ferrett Journal]

Princess and the Pea

There are few who will agree to have an air tank as part of an alarm clock. The Princess and the Pea concept uses compressed air to inflate an exercise ball in between the mattress and the box spring. Watch this video to see how it will roll you out of bed if the hissing air sound didn’t wake you first. At least it’s more gentle than the pneumatic alarm clock from last June. [via Neatorama]